#include <stdio.h>

int fib(int n) {
    if (n <= 2) {
        return 1;
    } else
        return fib(n - 1) + fib(n - 2);
}

int main() {
    int n = 0;
    scanf("%d", &n);
    int result = fib(n);
    printf("%d\n", result);
    return 0;
}
